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Issue 16, 2017
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Methylene-bridged, intramolecular donor–acceptor systems based on rare-earth metals and phosphinomethanides

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Abstract

New geminally bonded intramolecular donor–acceptor systems, Cp2LnCH2PR2 (Ln = Y, Ho, Er, R = CHMe2, CMe3), were prepared by salt elimination reactions between the dicyclopentadienyl-element chlorides (Cp2LnCl, Ln = Y, Ho, Er) and diorganylphosphinomethanides (R2PCH2Li; R = CHMe2, CMe3). These compounds, 1–6, were characterized by elemental analyses, mass spectrometry and X-ray diffraction experiments and the yttrium species additionally by NMR spectroscopy. In the solid state the molecular structures differ from each other, depending on the steric demand of the phosphorus substituents. For all iso-Pr-substituted compounds, dimers [Cp2LnCH2P(CHMe2)2]2 with six-membered Ln–C–P–Ln–C–P rings in a chair-like conformation were observed. The sterically more demanding tert-butyl groups prevent dimerization but instead lead to species that undergo complexation of LiCl units by two monomers: [Cp2LnCH2P(CMe3)2·LiCl]. The solution NMR data for the yttrium compounds are consistent with the solid-state structures. Conversion with phenylacetylene afforded heteroleptic cyclobutane-like alkynyl-rare-earth metal complexes [Cp2Ln(μ-C[triple bond, length as m-dash]CPh)]2 [Ln = Y (7), Ho (8), Er (9)]. Treatment of compounds 1–6 with 1,8-diethynylanthracene led to single metalation and dimerization and products with similar structural motifs as observed for complexes 7–9. Reactions with dihydrogen and carbon dioxide resulted in Y–C bond breaking, yielding Cp2YH/R2PCH3 and CO2 insertion products, respectively.

Graphical abstract: Methylene-bridged, intramolecular donor–acceptor systems based on rare-earth metals and phosphinomethanides

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Publication details

The article was received on 14 Feb 2017, accepted on 21 Mar 2017 and first published on 22 Mar 2017


Article type: Paper
DOI: 10.1039/C7DT00554G
Citation: Dalton Trans., 2017,46, 5326-5336

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    Methylene-bridged, intramolecular donor–acceptor systems based on rare-earth metals and phosphinomethanides

    M. Pieper, J. Lamm, B. Neumann, H. Stammler and N. W. Mitzel, Dalton Trans., 2017, 46, 5326
    DOI: 10.1039/C7DT00554G

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